I. Field of the Invention
The present invention relates generally to prefabricated, modular structures. More particularly, the present invention relates to dwellings or enclosures that are assembled from modular components substantially comprised of foam plastic, which are fitted together, prestressed and secured upon suitable concrete slabs or foundations to form an enclosure or habitable dwelling, or the like.
II. Description of the Prior Art
It has long been recognized by those skilled in the art that substantial advantages are obtained with modular construction techniques and apparatus. Typically. the construction and assembly of modular homes, for example, involves the shipment of preassembled, modular components to a building site at which a suitable foundation (i.e., a concrete slab) has been preestablished. Modules are designed to be coupled together, and diverse hardware accessories may be employed to securely join the various modules. Typically straps, hooks or cables are provided for securing the component modules to the foundation. Afterward, an inclined or gabled roof is constructed from similar modules or panels, which angularly interconnect with tops of the lower wall panels or modules that are fastened to the foundation.
In some designs the roof is tedious and cumbersome to install. A proper fit must be achieved between the various wall panels, for example, and the roofing elements which contact them. Joints must be contiguous and gap free. Trusses must be properly secured and tensioned. After assembly the integrated structure must be secure and durable, and it must be resistant to environmental forces such as rain, ultraviolet light, snow, ice and high winds. Adequate compensation must be provided for wide temperature shifts as well.
In relatively recent years prefabricated modules have been made of various forms of low density plastic, such as polystyrene or polyurethane foam, or expanded polystyrene foam i.e, EPS foam. Modular plastic construction modules have numerous advantages recognized in the art. Importantly, they are relatively lightweight, so transportation or shipping costs are reduced. Although some modules are bulky, their reduced weight eases the difficulty of manipulation and handling at the job site.
Properly designed plastic foam modules can exhibit favorable insulating characteristics, with minimal leak paths for unwanted heat losses. Thus the R-factor ratings associated with buildings or homes made of such plastic modules are significantly greater than those associated with conventional “stick-built” structures. Another advantage is that molded plastic modules may be relatively easily formed with integral coupling apparatus, such as mortise and tenon joints, or tongue and groove structures, for connecting them to adjacent modules or pieces. Structural integrity is further enhanced by the liberal use of modern adhesives that promote strength and form a dependable seal.
A wide variety of modular construction blocks, including blocks made of polystyrene plastic, exist in the art. For example, U.S. Pat. No. 4,633,634 issued Jan. 6, 1987 discloses a structure utilizing a plurality of expanded, polystyrene panels placed edge-to-edge and secured by connecting studs. Generally C-shaped channels in one panel are fastened in back-to-back relationship with similar channels in mating relationship within grooves of adjacent panels.
U.S. Pat. No. 3,778,949 issued Dec. 18, 1973 discloses synthetic plastic objects secured with reinforcing wires which are embedded in the body. Anchoring means in the form of wire sections extend from the region of the exposed surface to the reinforcing means and are connected therewith.
U.S. Pat. Application No. 20100242395 published Sep. 30, 2010 discloses insulating blocks adapted to be interlocked with other similar blocks to provide form insulating concrete forms for casting concrete.
U.S. Pat. Application No. 20100269439 published Oct. 28, 2010 discloses an insulated wall panel made of polystyrene foam blocks.
U.S. Pat. Application No. 20110165363 published Jul. 7, 2011 discloses panel elements made of plastic foam blocks which are arranged next to one another and connected to form foam bodies.
U.S. Pat. Application No. 20110214374 published Sep. 8, 2011 discloses a building panel utilizing a core with a frame and one or more polystyrene blocks.
Other modular construction blocks and/or building panels or structures are disclosed in U.S. Pat. No. 4,674,250 issued Jun. 23, 1987, U.S. Pat. No. 4,731,279 issued Mar. 15, 1988, U.S. Pat. No. 4,854,097 issued Aug. 8, 1989, U.S. Pat. No. 5,457,926 issued Oct. 17, 1995, U.S. Pat. No. 5,839,249 issued Nov. 24, 1998, U.S. Pat. No. 6,134,853 issued Oct. 24, 2000, U.S. Pat. No. 6,240,686 issued Jun. 5, 2001, U.S. Pat. No. 6,418,681 issued Jul. 16, 2002, U.S. Pat. No. 6,434,900 issued Aug. 20, 2002, U.S. Pat. No. 6,519,904 issued Feb. 18, 2003, U.S. Pat. No. 6,691,485 issued Feb. 17, 2004, U.S. Pat. No. 6,807,787 issued Oct. 26, 2004, U.S. Pat. No. 6,848,228 issued Feb. 1, 2005, U.S. Pat. No. 7,409,801 issued Aug. 12, 2008, U.S. Pat. No. 7,739,846 issued Jun. 22, 2010, U.S. Pat. No. 8,112,960 issued Feb. 14, 2012, and U.S. Pat. No. 8,127,509 issued Mar. 6, 2012,
Of course the art reflects a large number of modular buildings or enclosures that involve interconnected, modular blocks, including plastic blocks and panels. A variety of approaches exist for securing the blocks together, and for attaching panels to the foundation structure.
For example, U.S. Pat. No. 4,615,155 issued Oct. 7, 1986 shows a modular building employing floor, ceiling and roof modules constructed of at least two sheets of rigid, foamed, plastic material such as polyurethane and polystyrene. The sheets are offset laterally with respect to each other, providing a staggered construction. T-shaped plates with portions between the sheets are secured adhesively for reinforcement. The wall modules preferably have the two sheets overlying one another so that all edges of the sheets of the module are aligned and T-plates are secured to these edges. The wall modules may be provided with access openings, such as doors and windows, which are framed by T-plates.
U.S. Pat. No. 5,007,222 issued Apr. 16, 1991 discloses a load-bearing, prefabricated exterior walls and/or panels fabricated of light-weight foam surrounding plastic load-bearing columns. The hollow columns are set onto locking base plates which are mounted on a wood or concrete deck system. The tubular columns are made of a plastic material and are shaped in cross-section in the form of a rectangle, square, diamond, oval or circle. The hollow columns may be used as conduits for electrical wiring, water pipes and in certain cases can be fabricated to act as heat or air-conditioning ducts.
U.S. Pat. No. 5,664,386 issued Sep. 9, 1997 discloses interlocking, modular panels having a foam core with reinforcements. Contiguous panels meet and form a tight seam. During assembly the panels are slidable with respect to one another in a lateral direction.
U.S. Pat. No. 6,331,337 issued Dec. 18, 2001 illustrates the adhesive bonding of side-to-side building blocks to obtain modular sub-assemblies, walls, panels, floors, windows, skylights, etc. Flexible, light-weight, elongated, adhesive tape strips are used to adhesively bond together at least portions of complementary block surfaces.
U.S. Pat. No. 6,412,243 issued Jul. 2, 2002 depicts an ultra-lite, modular composite building system, comprising rigid, solid and expanded matrix materials that produce a functionally homogeneous, composite structure. The rigid material, as the primary structure capable of sustained axial stress, is encapsulated within the body of the matrix material as a sheet or membrane that is bonded to and braced by the matrix material. According to the invention, structures may be either thermoformed or extruded.
U.S. Pat. No. 6,931,803 issued Aug. 23, 2005 discloses a modular building system with a plurality of extruded plastic beams that are stacked and interlocked using a tongue and groove arrangement. Plastic connecting components are provided for interlocking the horizontal beams to a vertical column.
U.S. Pat. No. 7,412,805 issued Aug. 19, 2008 illustrates modular buildings comprising a foundation floor with a plurality of anchors, and a plurality of tracks secured to the floor that support various wall panels. A plurality of securing members passes through the channels or ducts to secure the panels.
U.S. Pat. No. 7,418,803 issued Sep. 2, 2008 discloses a modular home comprising a first section, a second section and a top section that are transported to a slab foundation and then erected on site. The modular home is secured to the slab foundation by a strap arrangement. Once the modular home arrives at the construction site, the home can bolted to the slab, made weather tight, and then connected to the local plumbing and electrical services.
U.S. Pat. No. 7,797,885 issued Sep. 21, 2010 discloses a modular enclosure in the form of a shed or small building comprising a plurality of interlocking panels that may be interconnected to form sidewalls, a roof and/or a floor. The panels may be constructed from blow-molded plastic.
U.S. Pat. No. Application No. 20080184649 published Aug. 7, 2008 discloses a modular enclosure made of interlocking and stackable, molded plastic blocks. Each building block has a tongue on one end and an insertion groove on another end. To form walls and slabs, the blocks are placed adjacent one other in interlocking position by inserting the tongue of the first block into the groove of the adjacent block.
U.S. Pat. No. Application 20100325988 published Dec. 30, 2010 discloses a modular structure for creating a substantially airtight, insulated building.
Other analogous modular and/or prefabricated structures with analogous blocks or panels are depicted in U.S. Pat. No. 4,813,193 issued Mar. 21, 1989, U.S. Pat. No. 4,823,534 issued Apr. 25, 1989, U.S. Pat. No. 4,924,641 issued May 15, 1990, U.S. Pat. No. 5,497,589 issued Mar. 12, 1996, U.S. Pat. No. 6,006,480 issued Dec. 28, 1999, U.S. Pat. No. 6,026,629 issued Feb. 22, 2000, U.S. Pat. No. 6,082,066 issued Jul. 4, 2000, U.S. Pat. No. 6,099,768 issued Aug. 8, 2000, and, U.S. Pat. No. 7,984,594 issued Jul. 26, 2011, U.S. Pat. No. 8,015,772 issued Sep. 13, 2011.
Another pertinent issue facing the designers or installers of modern, plastic block or panel structures involves the technique used for securing the blocks or panels together. The completed structure must be properly secured to the foundation, the composite blocks or panels must be properly secured together, and the resultant structure must be properly reinforced and braced. As mentioned above, straps or cables have been used in the past for anchoring and reinforcing various components. Numerous ancillary hardware items are used to reinforce or anchor plastic panels or blocks, and various forms of junctures are formed between the anchoring or connecting hardware and the blocks or panels.
For example, U.S. Pat. No. 3,778,949 issued Dec. 18, 1973 shows a synthetic plastic item with layers of wires embedded in the body for reinforcement and anchoring. U.S. Pat. No. 3,928,691 issued Dec. 23, 1975 shows reinforcing with ancillary rods. Here polyurethane cores are provided with semi-circular grooves that encompass iron or steel reinforcing rods that are captivated and sealed between abutting core members. U.S. Pat. Application No. 20040128776 published Jul. 8, 2004 discloses a tensioning arrangement for building components. An elongated wire cable anchored at its opposite ends in an end piece for absorbing the tensile forces exerted on the cable.
U.S. Pat. Application No. 20100300012 published Dec. 2, 2010 discloses building panels for residential and commercial construction comprising foam blocks connected by adhesive. A plurality of metal supports disposed on opposite sides of the blocks each have an external head portion in contact with the block surface, and an integral stem portion extending into the block. The supports are dimensioned such that the thermal conduction path established by the supports is discontinuous across the insulating block. Straps are commonly used in this for anchoring or strengthening the structure by prestressing components. For example, U.S. Pat. No. Application No. 20040107652 published Jun. 10, 2004 discloses reinforced, foam building components that form energy efficient structures assembled from panels. The structures are anchored to the foundation by straps passing through the panel assemblies. U.S. Pat. No. Application 20080229692 published Sep. 25, 2008 shows insulated, foam panels secured together with various straps.
U.S. Pat. No. Application 20100043315 published Feb. 25, 2010 discloses a network of tensioning straps extending over a framed structure and roof decking and terminating at the foundation. The strap network provides a distributed resistance force throughout the entire structure, enhancing its strength.
Other strap-equipped or prestressed modular systems using straps, brackets or the like are seen in U.S. Pat. No. 4,275,537 issued Jun. 30, 1981, U.S. Pat. No. 5,791,090 issued Aug. 11, 1998, U.S. Pat. No. 6,219,973 issued Apr. 24, 2001, U.S. Pat. No. 7,861,479 issued Jan. 4, 2011, and, U.S. Pat. No. 8,136,248 issued Mar. 20, 2012.
However, despite the above advancements associated with the use of modular foam building blocks or panels, many small, well known imperfections with such materials or components contribute to consumer apprehension and buyer resistance.
For example, plastic foam enclosures must be properly braced and adequately reinforced to satisfy building codes and to provide a safe, wind resistant structure. Of course there are prior art hardware structures, schmuck as those mentioned above, that are designed to brace such systems. However, the structural design of the panels or blocks must accommodate the bracing hardware, so that tensioning of cables, for example, does not break or fracture the panels. The stressing loads imparted by reinforcement cabling generates forces that must be adequately distributed about the structure to prevent damage or deformation. Where cables or straps are used, proper routing and mounting is necessary to insure that cable forces are properly diffused (i.e., distributed over contacted surfaces), so that foam components are not cracked or fractured. This is particularly true near anchoring points, for example, that originate at the concrete foundation, from which cables or straps extend over stacked modules or panels, often traversing roof sections.
Furthermore, maximum practicable structural integrity cannot be achieved with plastic foam panels or blocks alone, despite their inherent strength. Ancillary metal hardware items, such as rails, tracks, beams, channels, wall studs, frame elements and caps are commonly used for reinforcement. These items must be adequately coupled to or routed within the panels or blocks, in a non-destructive fashion. The proper application of load bearing struts or channels that promote tensile strength, for example, must proceed without slowing or unnecessarily complicating the building process. Furthermore, properly installed hardware items must not hinder the enclosure appearance, either inside or outside. Stated another way, the ancillary hardware associated with successful modular designs must be complementary with the plastic foam blocks or panels with which they are used. Each component, whether plastic or metal, must be designed to snugly interfit with, and nondestructively interact with the other. Most importantly, the inherent thermal conductivity of metal reinforcement structures promotes thermal inefficiency or losses, so that such structures must be properly integrated within the foam construction modules to break or minimize loss-inducing, conductive heat paths.